diff --git a/libc/include/semaphore.h b/libc/include/semaphore.h
index 4ef13af..218f22a 100644
--- a/libc/include/semaphore.h
+++ b/libc/include/semaphore.h
@@ -42,7 +42,7 @@
 #endif
 } sem_t;
 
-#define SEM_FAILED NULL
+#define SEM_FAILED __BIONIC_CAST(reinterpret_cast, sem_t*, 0)
 
 int sem_destroy(sem_t*);
 int sem_getvalue(sem_t*, int*);